1. Field of the Invention
The present invention relates to an illumination device for use as a backlight in a liquid crystal display device and a liquid crystal display device including such an illumination device.
2. Description of the Related Art
In recent years, products that incorporate, as a display device, a liquid crystal panel thinner than a CRT (cathode ray tube) have been widely used. Since the liquid crystal panel itself emits no light, it displays an image by the use of external light or light emitted from an illumination device.
Conventionally, cold cathode fluorescent tubes have been used as light sources in illumination devices for use in liquid crystal display devices. Today, LED (light emitting diode) lamps also come to be used. In illumination devices incorporating LED lamps as light sources, white LED lamps are used.
Disadvantageously, however, since white LED lamps vary widely in the color of light emitted therefrom, a liquid crystal display device that uses an illumination device incorporating LED lamps as a light source produces, for example, reddish or bluish display, that is, it has poor color rendering properties. JP-A-2002-231032 (page 3, FIG. 1) proposes a backlight that has a light guide plate and uses white LED lamps as a light source disposed on the side of the light guide plate and that subjects either the light guide plate or a reflective plate disposed on the back of the light guide plate to coloration reflection treatment corresponding to the color of light emitted from the white LED lamps and thereby performs color correction.
Disadvantageously, however, the backlight proposed in JP-A-2002-231032 is required to modify and adjust the coloration reflection treatment on a white-LED-lamp's-color-by-white-LED-lamp's-color basis. Only white LED lamps of the same color need to be used; white LED lamps of different colors cannot be used. Moreover, the backlight can only be used as a sidelight backlight, in which LED lamps are disposed on the side of a light guide plate; it cannot be used as a direct-type backlight, in which a larger amount of light emitted therefrom is obtained.